In an image forming apparatus such as a laser printer, various kinds of rollers that rotate along with a feeding operation of a recording medium such as a sheet of paper (hereinafter referred to as a recording sheet) are disposed. Of these rollers, for example, a heat roller that is configured to heat a developing agent image transferred onto a recording sheet receives a driving force via a gear train composed of gears.
The image forming apparatus is generally provided with a body frame. The body frame includes side frames disposed on both sides of the image forming apparatus, with respect to a width direction, which is horizontal to a direction perpendicular to a sheet feeding direction. In a space defined between the side frames (hereinafter referred to as an installation space), an image forming device including a fixing unit and process cartridges is detachably attached to the side frames.
Gear trains are assembled on the outside of the body frame as opposed to the inside of the body frame where the installation space is defined. The outside of the body frame is covered with a cover plate so as to protect the gear trains.
The outside of the cover plate is covered with a design cover (or a housing) that provides the cosmetic appearance of the image forming apparatus. Circuit boards such as a control circuit board and a power circuit board are disposed between the cover plate and the body frame.
Thus, if a gear that drives the heat roller is greatly worn or damaged and needs replacing, the design cover should be removed to remove the cover plate and the circuit boards before replacing the gear.
After replacing the gear, the cover plate and the circuit boards are assembled to the body frame, and then the design cover is assembled to the body frame.